PURPOSE: To enhance the accuracy of a torque meter by resetting the torque meter during use of a bicycle thereby making the zero point variable depending on a physical disturbance.

CONSTITUTION: Means 9 for detecting the angular position of a drive wheel 6 around the spindle 4 of the hub 11 is combined with means 12 for detecting the angular position the drive shaft 6 around the axis of a rim 13. A monitor means for detecting stoppage of rotation of the pedal crank gear 8 of a bicycle comprises a combination of a permanent magnet 15 fixed to the inner surface of the ring of the gear 8 and a magnetic effect motion sensor 16. In the case of a bicycle having a drive wheel provided with a free wheel mechanism, a user can stop the rotation by stepping a pedal at the time of a high speed and no torque is transmitted to the drive wheel 6 at that time. Consequently, a torque meter can be reset at that moment of time.